This invention relates generally to optical coupling of light sources and light pipes; and more particularly concerns endwise optical coupling of LEDs to fiber optics light pipes in a simple and effective manner to maintain their coaxial relationship during light transmission from the LED to the light pipe, as will appear.
There is need for improvements in apparatus, and methods, to overcome difficulties in optical coupling as between light sources and light pipes; and there is need to improve light transmission between and by these elements. Also, there is need to provide for diffusion of light transmitted by light pipes, and especially where light of different colors is to be transmitted and mixed.
It is a major object of the invention to provide improvements in such optical coupling, as will meet the referenced needs.
Basically, the light transmission device of the invention comprises, in combination:
a) a longitudinally axially extending light pipe having opposite ends,
b) one of those ends having a light diffusing surface.
As will appear the other of the light pipe ends may also have a light diffusing surface to enhance the desired light diffusing effect, and the light pipe typically has a wall along its length that is light reflecting.
Another object is to provide facets at one of the light pipe ends, such as the end that transmits light from the light pipe, and such facets may advantageously comprise Fresnel rings. The surfaces of the latter may be scored to provide a diffusing surface of the light pipe end.
A further object is to provide a recess at the end of the light pipe that receives light from the LED. As will appear, the surface of that recess may also or alternatively be scored to provide for light diffusion. The recess may typically be dished, and define a concavely curved inner wall via which light is transmitted into the light pipe. Further, the light source may typically have a flat or convex portion thereof received into the recess, whereby the recess defines a perimeter extending about the light source. The light source may be attached, as by surface mounting, to a printed circuit board, and the light pipe end recess typically defines a perimeter that projects toward said board, sidewardly of the light source which comprises an LED.
It is another object of the invention to provide a light source comprising an LED having at least two emitters of light of different wavelengths. For example the emitters may comprise red and yellow light emitters, such light being mixed in response to diffusion by the end or ends of the light pipe, to produce a resultant amber output.
A further object includes provision of a support panel carrying the light pipe, in spaced relation to said recess. The faceted opposite end of the light pipe typically terminates proximate the panel, and a pipe flange engages one side of the panel. A grip ring may be provided for gripping the light pipe and engaging the opposite side of the panel.
The method of diffusing light transmitted by a light source and light pipe, in accordance with the invention, includes the steps
a) providing a light pipe support,
b) assembling the light pipe to the support, and
c) assembling the light pipe and light source so that the light source projects at an end portion of the light pipe in spaced relation to the support,
d) the light pipe having opposite ends, at least one of such ends provided with a light diffusing surface.
Additional objects include providing the opposite end of the light pipe with a light diffusing surface; providing a recess at an end of the light pipe, and assembling the light pipe and light source to receive a portion of the light source into said recess; providing the recess to have a concave inner wall facing the light source; providing facets on an end of the light pipe; providing light diffusing surfaces on said facets; providing grip structure gripping the light pipe; providing a flange on the light pipe, and locating a panel to extend between said grip structure and flange, to be engaged thereby; and providing the light source to comprise an LED having at least two emitters of light of different wavelengths.